1. Field of the Invention
This invention is directed to a method and apparatus for maintaining pressure within a product dispenser. In particular, the present invention is directed to a unique method and apparatus which, when pressure within a container is reduced by the dispensing of product, automatically regenerates the pressure within the dispenser so as to re-establish sufficient pressure for dispensing of the product.
2. Background of the Invention
In recent years various efforts have been exerted to supplant conventional aerosol-type dispensers, which used hydrocarbons such as isobutane, or fluorocarbons such as freon, with other propellant means. Thus, a variety of considerations, including cost, wasted product and flammability, have prompted considerable research and development activity aimed at finding alternative means to dispense various flowable material products.
The use of a fluid impervious, expandable bag containing gas generating components, such as that described in U.S. Pat. No. 4,376,500 issued to Banks et al., produces a relatively constant expulsion pressure during use, and overcomes certain problems existent in the prior art. In the Banks et al. patent, as described, the dispensing system expels flowable material product in a uniform spray. However, this known system is complex in that it requires the production of a multi-cavity enfoldment which must have the proper amount of acid disposed in each cavity for regenerating pressure when interacting with the citric acid sodium bicarbonate. In addition, the releasable seals must be properly oriented so that the enfoldment releases the sodium bicarbonate of the proper number of cavities with each occurrence of the dispensing of product. Therefore, it is a difficult and complex task to ensure that the apparatus will regenerate a pressure within the dispenser which corresponds approximately to the starting pressure or initial pressure within the dispenser.